HITEC: 107 oz/in torque ($73) ... GWS: 111 oz/in torque ($10)?

[S. Karim]

http://www.pololu.com/products/servos.html

Has anyone ever seen this? Is either pololu or GWS durable?

Check the orange table for GWS S03T...111 oz/in for 10 dollars. Anyone can verify this things durability? Where can I get more info on it's gear type? For 10 dollars, they're sure to be nylon.

[Eco19R]

you also need to look at rotation speed of the servo horn.

[S. Karim]

? Im not sure I understand. 0.27sec for 60 degrees isnt bad at all. I'm asking if anyone has any more info on these GWS servos, as in gear-type and trustability in the company's products?

[Eco19R]

I wasn't commenting on that servo - all I said was you need to take rotation speed into account also  when looking to purchase.

[S. Karim]

ah ok. what does that have to do with my question though? ive never bought servos before so what is it about rotation speed exactly that you're trying to imply?

[Eco19R]

If your looking to make a biped the maximum movement speed of it is affected by the maximum rotation speed of the servos. Rotation speed is just as important as torque in certain situations depending on the application.


 it seems you would also want to have the servos be all the same to eliminate syncing problems

[Admin]

it seems you would also want to have the servos be all the same to eliminate syncing problems

True for the knee and hip servos, but you can probably get away with cheaper/smaller/weaker servos for the upper body of a biped and perhaps the ankles.

[S. Karim]

im going to buy all motors the same.

admin, whats your insight on these GSW motors? trust or not?

[Admin]

Ive never used them, but also never heard anything bad about them.

But as Eco19R said, they are also much slower. You should sit down and do some math to figure out what joint rotation speeds are acceptable.

[S. Karim]

0.27 sec/60 degrees.

since i dont have any perception of what this will really look like, im going to assume it takes half a second to rotate 60 degrees. isnt that quite fast?

when the motors have load, how long could it possible take to walk (assuming the robot is heavy)? if the robots frame is heavy...i do need strong motors right?

hows the GWS MINI sound?

4.8V (SPEED/TORQUE)

0.19    47    

6V (SPEED/TORQUE)

0.15    58

0.15 is faster, but only 58 oz/in. Is this enough to propel legs?

[Admin]

0.27 sec/60 degrees

Thats .62 rotations per second. This is without load, so in reality its going to be much slower.

if the robots frame is heavy...i do need strong motors right? . . . 0.15 is faster, but only 58 oz/in. Is this enough to propel legs?

All I can say is, calculate it. You will have to do things like estimate total robot weight, and know the lengths of various leg parts. If you have trouble I can hint you in the right direction.

[S. Karim]

k thanks a bunch. they got back to me and said the GWS standard servo with 111 oz/in is nylon gear based...so since thats the weakest im not sure whether im still going to purchase them or not.

[sotu]

I think Pololu is reliable, i have ordered something from them myself and there shipping time is also very impressive..